In a statement, the Iranian government said that the 11 had been arrested in the embassy as Iranian security officials cleared the compound out. They were among as many as 15 who were arrested. In a statement, the Iranian Foreign Ministry blamed the incident on the students' “passion,” saying that “The student protests at the British embassy in Tehran grew out of control. The ministry expresses its regret over the unacceptable behavior of a few protestors, which went on despite the efforts of security forces to stop them.”

But Western officials were not impressed. As Iran released the rioters – apparently with no charges filed – on Thursday, EU leaders were meeting to discuss the possibility of increasing sanctions on Iran. In the wake of the Tehran riot, Britain has removed its diplomatic personnel from Tehran and has sent the Iranian ambassador in London packing; both France and Germany recalled their envoys from Iran; and numerous European countries called in the Iranian ambassadors to their capitals, telling them to warn their government that they would not sit still for such treatment.

Now, EU officials are considering an oil embargo on Iran, preventing the shipping of Iranian oil to the West. The idea has been under consideration since the latest IAEA report on Iran's nuclear weapon aspirations several weeks ago, but the occupation and sacking of the British embassy has pushed the idea to the forefront of the EU's agenda.

Western experts say that preventing Iran from exporting oil to Europe and other countries could be a “death-blow” to the Iranian economy. Speaking to Bloomberg, Javad Salehi-Isfahani, a professor of economics at Virginia Tech, said that other than oil, the Iranian economy is in very bad shape. People have money, they have enough to eat, but they don’t have jobs.” Closing off what is perhaps Iran's only reliable source of foreign income could convince the Iranian people to finally attempt to rise up against the regime en masse, he said.

It was unclear if the ministers would agree to a boycott. Speaking before the meeting, German Foreign Minister Guido Westerwelle said sanctions against Iranian oil could prevent Tehran from continuing with its nuclear program, and that should be the point of sanctions. But British Foreign Secretary William Hague, when asked by a reporter if a boycott was on the agenda, would only say that he was "sure we will agree on a range of measures.”

In an interview in the British media earlier Thursday, Hague said that the new sanctions are "not measures that are in reaction to our embassy. There has been a range of other reactions to that. Our long-term concern is, of course, the nuclear programme, the danger that poses to the peace of the Middle East and the wider world, the threat of proliferation spreading to other countries in the region. It is for that reason we will agree, I hope, today to intensify European sanctions on Iran."